1, 3-Dipolar cycloaddition reaction of nitrilimines with 5-arylidene-1, 3-dimethyl-2, 4, 6- pyrimidinetriones 1a–i afforded 7, 9-dimethyl-1, 3, 4-triaryl-1, 2, 7, 9-tetraaza-spiro [4.5] dec- 2-ene-6, 8, 10-triones 3a–k in a high regioselective manner. Single crystal X-ray study of 3d